Gold dragons are the ones most often killed by humans, who consider their scales to be extremely valuable. These golden scales grant them a high level of protection, similar to armor, and they use this to their advantage in battle.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

Tanjiro, while not biologically related to Kuen, grew up with Kuen acting as his older brother. Tanjiro seamlessly slipped into the role of the enthusiastic, occasionally irritating younger sibling.

Tanjiro lives in a deep cavern with his brother. While they share a hoard, Tanjiro is doubtlessly the top contributor. He has a blatant obsession with any shiny, manmade object, and has many patches on his sides where the trading caravans or camps he's pillaged in the middle of the night have struck back at him, ripping the scales from his body. Kuen tries his absolute hardest to discourage this behavior. As of yet, he's only been able to shake his head, deliver a lecture, and work to heal Tanjiro's bloody wounds. Tanjiro at the very least has avoided leading unwanted trespassers back to the duo's lair. A raiding party discovering their cave could lead to the brothers' untimely demise. While their cavern is large, it is by no means big enough to allow for the advantage of flight.